It is often necessary to humidify or moisten dry particulate materials prior to further use of the materials. For example, expanded tobacco is typically reordered by permitting the tobacco particles to reside in a humid atmosphere or by conveying the tobacco particles on a conveyor through a humid atmosphere for a necessary period of time. Unless the tobacco is moved about through the humid atmosphere, the residence time in the humid atmosphere can be prohibitively time consuming.
Equipment such as the rotary tobacco treatment cylinder disclosed in U.S. Pat. No. 5,425,384 can be used to rapidly reorder tobacco. One problem with such equipment is that, when the cylinder is too large, it tends to degrade the tobacco particles because the particles fall from blades on the interior of the cylinder to the bottom of the cylinder over a great distance. When the cylinder is made smaller, the capacity of the cylinder is reduced. It is desirable to provide a reordering device that permits rapid reordering of large quantities of tobacco while minimizing degradation of the tobacco.
In accordance with one aspect of the present invention, a humidifying cylinder includes a first rotatable cylinder having an inlet end and an outlet end and a plurality of first blades extending substantially radially outwardly from an exterior surface of the first cylinder. The humidifying cylinder further includes a second rotatable cylinder having an inlet end and an outlet end and a plurality of second blades extending substantially radially inwardly from an interior surface of the second cylinder, the second cylinder being substantially coaxial with the first cylinder and the first cylinder being disposed inside of the second cylinder such that the exterior surface of the first cylinder and the interior surface of the second cylinder define an annular space. At least one drive is provided for rotating the first cylinder and the second cylinder. At least one conduit is disposed in the annular space for introducing moisture into the annular space. A method of humidifying material is also disclosed.
In accordance with another aspect of the present invention, a method of humidifying material is disclosed. According to the method, material is introduced into an annular space between a first rotatable cylinder having an inlet end and an outlet end and a plurality of first blades extending substantially radially outwardly from an exterior surface of the first cylinder and a second rotatable cylinder having an inlet end and an outlet end and a plurality of second blades extending substantially radially inwardly from an interior surface of the second cylinder, the second cylinder being substantially coaxial with the first cylinder and the first cylinder being disposed inside of the second cylinder such that the exterior surface of the first cylinder and the interior surface of the second cylinder define the annular space. The first cylinder and the second cylinder are rotated such that, as the second cylinder is rotated, material falls from at least some of the second blades onto the first cylinder and, as the first cylinder rotates, material falls from at least some of the first blades onto the second cylinder. Material is conveyed in the annular space from the inlet end of the first cylinder and the inlet end of the second cylinder toward the outlet end of the first cylinder and the outlet end of the second cylinder. Moisture is applied to material in the annular space.